A Brief Overview of the Trans-Atlantic Slave Trade

David Eltis(Emory University),
2007

The Middle Passage

Whatever the route taken, conditions on board reflected the
outsider status of those held below deck. No European, whether
convict, indentured servant, or destitute free migrant, was ever
subjected to the environment which greeted the typical African
slave upon embarkation. The sexes were separated, kept naked,
packed close together, and the men were chained for long periods. No
less than 26 percent of those on board were classed as children, a
ratio that no other pre-twentieth century migration could come close to
matching. Except for the illegal period of the trade when
conditions at times became even worse, slave traders typically
packed two slaves per ton. While a few voyages sailing from Upper
Guinea could make a passage to the Americas in three weeks, the
average duration from all regions of Africa was just over two
months. Most of the space on a slave ship was absorbed by casks of
water. Crowded vessels sailing to the Caribbean from West Africa
first had to sail south before turning north-west and passing
through the doldrums. In the nineteenth century, improvements in
sailing technology eventually cut the time in half, but mortality
remained high in this period because of the illegal nature of the
business. Throughout the slave trade era, filthy conditions ensured
endemic gastro-intestinal diseases, and a range of epidemic
pathogens that, together with periodic breakouts of violent
resistance, meant that between 12 and 13 percent of those embarked
did not survive the voyage. Modal mortality fell well below mean
mortality as catastrophes on a relatively few voyages drove up
average shipboard deaths. Crew mortality as a percentage of those
going on board, matched slave mortality over the course of the
voyage, but as slaves were there for a shorter period of time than
the crew, mortality rates for slaves (over time) were the more
severe. The eighteenth-century world was violent and
life-expectancy was short everywhere given that the global
mortality revolution was still over the horizon, but the human
misery quotient generated by the forced movement of millions of
people in slave ships cannot have been matched by any other human
activity.